Oxygen (O2) - constitutes approximately 21% of the air we breathe, has a gaseous specific gravity of 1.105 makes it slightly heavier than air, and has a boiling point of –297.3°F (-183°C), it becomes a transparent, pale blue liquid that is slightly heavier than water. Oxygen also colorless, odorless and tasteless & has poor solubility in water.

The principal uses of oxygen are indicative of its strong oxidizing and life-sustaining properties. It’s used in medicine for therapeutic purposes and used in treatment of patients with respiratory disorders. In the chemical and petroleum industries, o xygen can be used as a chemical reactant and in combustion systems to have increased reaction rates, yield improvements, reduced capital cost of new plants and reduced air emissions. Furthermore, in acid sulfuric mill, oxygen use to alter the structure of feedstocks through oxidation, producing nitric acid, ethylene oxide, propylene oxide, vinyl chloride monomer and other building block chemicals.

Oxygen is used in the pulp and paper industry for a variety of applications, including pulp bleaching, black liquor oxidation and lime kiln enrichment.

Oxygen is frequently employed in iron, copper and lead blast furnaces, iron melting foundry cupolas and rock or slag-melting cupolas to increase productivity by increasing combustion temperatures and reduce the specific coke consumption. In metal cutting application, is use to support oxyfuel cutting operations. Oxygen/fuel combustion is used in the glass industry to reduce particulate and Nitrogen Oxide (NOx) emissions in melting operations.

In waste water/water treatment, oxygen can be used in place of air in the activated sludge process to maintain a higher population of micro-organisms. Using oxygen injected through a side stream instead of using a mechanical aerator eliminates surface agitation, reducing odour. Injecting oxygen into pumped sewer mains maintains the sewage in an aerobic state, preventing formation of hydrogen sulphide.

Nitrogen (N2) - makes up 78.03% of air, has a gaseous specific gravity of 0.967 and a boiling point of –320.5°F (-195°C) at atmospheric pressure. It is colorless, odorless, non-toxic and chemically inert . Nitrogen is non-flammable and capable of suppressing combustion processes. In addition, as an inert gas it has an asphyxiating effect, as it displaces the oxygen required for breathing Nitrogen has numerous applications in the industrial and research sectors because of its nonreactive nature with many materials.

In the chemical and petroleum industries, gaseous nitrogen applications include inerting reactors and storage tanks, purging vessels and pipelines of flammable or toxic gases and vapours, and the sparging and pressure transfer of liquids. While in electronics field, it is used in the inerting of printed circuit board reflow and wave ovens, to prevent oxidation and facilitate the use of weaker fluxes that decompose more easily without leaving a residue

In metals industry, nitrogen is used in iron and steelworks applications for degassing and metal-stirring, purging, cooling, slag splashing, gas knives and as a carrier gas for injecting de-sulphurising compounds. It is also used for aluminium-extrusion inerting. For lasers cutting, nitrogen is used as an assist gas for laser cutting of stainless steel, aluminium and non-metallic materials

Food Industry use Liquid nitrogen freezes food & goods such as car tyre quickly, producing a higher-quality product. In addition, Nitrogen is used in brewing, soft drinks and wine-making industries to exclude air from the product and de-aerate water. The nitrogen keeps oxygen from damaging stored foods, preventing fats' and other nutrients' decomposition.

Medical industry will use nitrogen in Cryosurgery, where Nitrogen is used to safely remove skin lesions such as warts, tags and verrucas in both humans and animals by the use of spray tips or probes attached to a cryogenic applicator. Furthermore, Liquid Nitrogen can be used to store medical sample such as blood, plasma & semen.

Heat treatment, pure nitrogen is used to protect some of the most reactive metals during heat treatment. These metals readily form a protective oxide surface layer from the small amount of oxygen in the nitrogen and need no further protection.

Another interesting nitrogen applications is shrink-fitting that Liquid nitrogen is used to shrink components so they are small enough to be inserted into another component.

Argon is a chemically inactive and belongs to the family of inert gas. It is 1.38 times heavier than air. It is odorless, tasteless, colorless, non-toxic, non-combustible, non-corrosive and does not react with other elements or chemical compounds.

Argon is widely used in incandescent lamp industry or the filling of light bulbs and fluorescent lamp. Furthermore, it also used with other rare gases in filling of special bulbs and display tubes for lighted signs. It is used to provide an i nert gas shield for arc welding (GMAW (MIG) & GTAW (TIG)) to prevent oxidation of the metal being welded. In plasma gas cutting, argon or Argon-H2 heated to certain temperature that used for cutting operation and for coating metals with refractory material. In addition, argon also used in refining of stainless steel, dehydrogenizing refining of melted aluminium, silicon ingot production, semiconductor fabrication, powdered metal fabrication and as a carrier gas for various analytical instrument.

Acetylene (C 2H2) is a compound of carbon and hydrogen. A colorless flammable gas with a garlic-like odor. It is slightly lighter than air. It’s combustion with oxygen may produces a flame with temperature of approximately 3150°C, allowing it to be used in welding, cutting, brazing, heating and soldering metals. The oxy-acetylene torch can be used to repair ships underwater, to construct bridges, pipelines, dams, tunnels, buildings and to reinforce concrete. When used with either oxygen or air, acetylene can produce a thin layer of black carbon particles. This can prevent components sticking in their moulds and help on mould release. In laboratory, acetylene is u sed in optical spectrometry as an instrumentation gas; used in atomic absorption for elemental analysis as an instrumentation gas; and used as a fuel gas in atomic absorption spectrometry for elemental analysis.

CAS number

74-86-2

Molecular weight

26.0

Empirical formula

C 2H2

Common synonyms

Ethenylene, Ethine, Ethyne, C2H2, Vinylene

State at room temperature

Gas

Volatility

Vapour pressure; 5240 mm Hg at 25 oC

Specific gravity

0.9 (air = 1)

Flammability

Mixes well with air. Extremely flammable in the present of open flames, sparks, heat and oxidizing materials.

Mixture with air containing between 3-82% gas is explosive. Reactions with oxidants are usually violent or explosive if uncontrolled.

Reaction or degradation products

Decomposes on heating and increasing pressure, causing fire and explosion hazard. Its decomposition products include hydrogen gas (flammable), carbon monoxide and carbon dioxide. Strong reducing agent and reacts violently with oxidants and with fluorine or chlorine under influence of light, causing fire and explosion hazard. Reacts with copper, silver, and mercury or their salts, forming shock-sensitive compounds (acetylides).

Odour

Odourless, although garlic-like or gassy odour due to trace impurities

Structure

1

Industrial Gas - Carbon Dioxide

Carbon Dioxide (CO2) is a nonflammable, colorless, odorless and liquefied gas. Carbon dioxide gas is relatively nonreactive and nontoxic. It exist simultaneously as a solid, liquid and gas at a temperature of –69.9°F (-56.6°C) and a pressure of 60.4 psig (416 kPa). At the temperature of -110°F (-79°C) and 1 atmospheric pressure, carbon dioxide solidified & forming the “dry ice” at a density of 97.4 pounds per cubic foot.

Carbon dioxide is widely used in food and beverages industry. It is the source of the bubbles in soft drinks and other carbonated beverages. As a natural anti-microbial, carbon dioxide is also used to increase the shelf life of juice and dairy products, protecting taste and texture, and reducing the need for preservatives, natural and artificial. In addition, as a “dry ice” it also used in food freezing and chilling and packaging, mixer and blender cooling, and in-transit refrigeration.

Carbon dioxide commonly used as a shielding gas during MAG welding because it prevents atmospheric contamination of molten weld metal during gas shielded electric arc welding process. Besides, it is also used for CO2 lasers in welding and cutting. Carbon dioxide also play an important roles in many industrial process grinding sensitive material, rubber tumbling , cold-treating metals, shrink fitting of machinery parts and industrial cleaning by blasting and polishing.

It is used to fill certain types of fire extinguishers that rely on its inert properties, density, and low temperature when released from high-pressure storage.

Injection of carbon dioxide allows to master the pH of liquid effluents. It's safer and cheaper than sulfuric-acid systems, improves controllability, and there is less downtime and no labor to handle chemicals. It also is less corrosive, and easier to handle and store. CO2 is an excellent alternative to sulfuric acid for pH balance control.

Large quantities of hydrogen is used in chemical syntheses mainly to manufacture ammonia and methanol, furthermore it also used to hydrogenate non-edible oils for soaps, insulation, plastics, ointments and other special chemicals. In food industry hydrogen is used to hydrogenate edible oils such as soybean, fish, cottonseed and corn, converting them to semisolid materials such as shortenings, margarine and peanut butter.

Hydrogen is used with oxygen in oxyhydrogen welding and cutting in certain brazing operation, welding aluminium and magnesium especially thin sections and welding lead. In addition, it commonly mixed with argon for welding austenitic stainless and also used to support plasma welding and cutting operations.

Hydrogen is a carbon-free energy source used in the fuel cells that create electricity through an electrochemical process in combination with oxygen.

Hydrogen is used as carrier gas in semiconductor processes, especially for silicon deposition or crystal growing and as a scavenger gas in atmosphere soldering as well as for annealing copper films. The use of forming gases (that is H2 diluted in nitrogen) allows virtually a complete elimination of oxygen and its inconveniences in medium to high temperature processes.

Hydrogen is used for desulfurization of fuel-oil and gasoline from crude oil in petroleum recovery and refinery. For power generation, large electrical generators are sometimes run in a hydrogen atmosphere to reduce wind age losses and remove heat.

Helium (He) is a colorless, odorless, tasteless inert gas at room temperature and atmospheric pressure. It is the second-lightest eleme nt found in earth so far with the gaseous specific gravity of 0.138. It’s boiling point is –452.1°F ( -268.9°C) at atmospheric pressure. It is a rare gas in the atmosphere

Helium is widely used in the welding industry as an ideal shielding gas for arc welding (GTAW & GMAW) especially with stainless steel, aluminum, copper, nickel, titanium and many alloys . It is also extensively used in filling of balloons (Helium Balloon Gas) for upper atmosphere and cosmic studies, weather forecast and advertisement purpose.

Helium is the most commonly gas used as carrier in gas chromatography. Helium's molecules are extremely small, making it a perfect leak detection gas to ensure no leaks in pressure and vacuum systems . Liquid helium is also used as a cooling fluid in superconducting magnet applications for the MRI, NMR or EPR . In addition, it also used in CO2 lasers.

A mixture of helium and oxygen finds use as a breathing gas in deep-sea diving. Besides, it also use in a medical for therapy and anesthesia of patients suffering from asthma.

SIG provides a series of shielding gas mixtures that meet the stringent requirements of for MIG (GMAW), TIG (GTAW), plasma cutting & welding and robotic applications. All these shielding gas will increase the efficiency of the welding process:-